Math

9X x 9X (tens digit is 9, units digit is 0-9)

Formulas :

First digits = 100 - [( 100 - 9__ ) + ( 100 - 9__ )]

Second digits = ( 100 - 9__ ) × (100 - 9__ )


Example :

97 × 96


First digits = 100 - [( 100 - 97 ) + ( 100 - 96 )]

= 100 - 7

= 93

Second digits = ( 100 - 97 ) × ( 100 - 96 )

= 12


So, 97 × 96 = 9312



XX x XX (any 2 numbers)

Formulas :

( __ x __ )[( __ x __ ) + ( __ x __ )]( __ x __ )


Example :

51 × 63

( 5 × 6 )[( 5 × 3 ) + ( 1 × 6 )]( 1 × 3 )

(30)[( 15 + 6 )](3)

(30)(21)(3)


So, 51 × 63 = 3213